Image Based Rendering (IBR) is a method generating novel scenes from a set of reference images. The reference images are actual pictures of an object and color may be calculated from pixels in the reference images. Thus, IBR is a method for achieving photo realism. Image-based Visual Hull (IBVH) is a type of Image Based Rendering that may be used to reconstruct three-dimensional (3D) models from a group of reference images of an object. A conventional IBVH technique involves a 3D reconstruction method that takes a group of pictures as input, and produces a convex hull of the target object.
The conventional IBVH technique uses the object silhouette in reference images to recover the geometry information. However, a problem with this conventional technique is that the silhouette is not capable of revealing information of a concave region on the surface of an object (i.e., referred to as a concave object). Consequently, the concave object is difficult to reconstruct. In particular, the conventional IBVH technique can lead to a protuberant defect and subsequently diminished photo-realism. An example of a reconstructed object having a protuberant defect is shown in FIG. 2. The development of a protuberant defect is partly because the concave region is always surrounded by the rest of the object. Consequently, the conventional IBVH technique has problems in acquiring the geometry of the concave object with reference images.